Apparatuses, systems, and methods for gas leak detection

ABSTRACT

Methods, apparatuses, and systems for providing a position sensing component are disclosed herein. An example sensor assembly may comprise: a primary sensing device, a reference sensing device located in proximity to the primary sensing device; and a flue coupled with one of the primary sensing device and the reference sensing device to provide a pathway for a first gas in a first area to access the one of the primary sensing device and the reference sensing device. The one of the primary sensing device and the reference sensing device is coupled to the flue and is configured to determine a first concentration level of the first gas in the first area. The other of the primary sensing device and the reference sensing device is configured to determine a second concentration level of the first gas in a second area.

TECHNOLOGICAL FIELD

This disclosure generally relates to methods, systems, and associatedsensor assemblies for monitoring gas leaks and, more specifically, tosensor assemblies for monitoring and detecting refrigerant gas leaks.

BACKGROUND

Refrigeration units include refrigerant coils that contain flammablerefrigerants. Due to the flammability of the refrigerants, leaks may bedangerous and therefore need to be detected before a sufficient amountof refrigerant leaks, providing the potential for fire or explosions.Through applied effort, ingenuity, and innovation, many of theseidentified problems have been solved by developing solutions included inembodiments of the present disclosure, many examples of which aredescribed in detail herein.

The foregoing illustrative summary, as well as other exemplaryobjectives and/or advantages of the disclosure, and the manner in whichthe same are accomplished, are further explained in the followingdetailed description and its accompanying drawings

SUMMARY

In accordance with various examples of the present disclosure, variousexample methods, apparatuses, and systems for monitoring gas leaks maybe provided.

In some examples, a sensor assembly may be provided. The sensor assemblymay comprise: a primary sensing device, a reference sensing devicelocated in proximity to the primary sensing device; and a flue coupledwith one of the primary sensing device and the reference sensing deviceto provide a pathway for a first gas in a first area to access the oneof the primary sensing device and the reference sensing device. In someexamples, the one of the primary sensing device and the referencesensing device is coupled to the flue and is configured to determine afirst concentration level of the first gas in the first area. In someexamples, the other of the primary sensing device and the referencesensing device is configured to determine a second concentration levelof the first gas in a second area.

In some examples, the reference sensing device and is configured toreceive the determined first gas concentration level of a first gas andsecond gas concentration level of a second gas from the primary sensingdevice and the reference sensing device, compare the first gasconcentration level and the second gas concentration level to determinea reading difference, and based on the comparison, in an instance inwhich the second gas concentration level and the first gas concentrationlevel have a reading difference greater than a predetermined thresholddifference to cause a transmission that a leak of the first gas isoccurring.

In some examples, the primary sensing device and the reference sensingdevice are exposed to identical exposure of environmental variables. Insome examples, the sensor assembly further comprises a filter positionedon one side of the flue, wherein the filter is configured to screen outone or more gases from reaching the reference sensing device. In someexamples, the primary sensing device is adapted to be exposed to apotential leak source and the reference sensing device is adapted to beexposed to an environment other than the potential leak source underidentical environmental variables.

In some examples, the threshold difference is based on between 5% and10% of a volume of the first gas. In some examples, the thresholddifference is based on a flammability level of the first gas. In someexamples, the first gas is a refrigerant. In some examples, the sensorassembly is further configured to receive one or more environmentalvariables and correcting the first gas concentration level reading andthe second gas concentration level reading based on the environmentalvariables.

In some examples, the control circuitry comprising at least oneprocessor, the at least one processor having computer coded instructionstherein, with the computer instructions configured to, when executed,provide an alert signal. In some examples, the sensor assembly is afully analog system or a digital system. In some examples, a size of theflue is designed such that a mean free path of the gases being sensed isnot encroached.

In some examples, a diameter of the flue is about 100 times the meanfree path. In some examples, a response time of the sensing is adaptedto remain within acceptable limits based on a length of the flue,wherein the length of the flue is about 0.1 meter to 3 meters.

In some examples, a method of determining a gas leak with a sensorassembly may be provided. In some examples, the sensor assembly maycomprise a primary sensing device and a reference sensing device. Insome examples, the method may comprise determining, via a flue extensioncoupled with a reference sensing device, a first gas concentration levelof a first gas in a given area; determining, via a primary sensingdevice, a second gas concentration level of a second gas in the givenarea; comparing, using a control circuitry, the determined first gasconcentration level and the second gas concentration level; and based onthe comparison, in an instance in which the first gas concentrationlevel reading and the second gas concentration level reading have ameasured difference greater than a predefined threshold difference,causing a transmission of a differential output that a gas leak isoccurring.

In some examples, the method includes exposing each of the primarysensing device and the reference sensing device to identicalenvironmental variables, wherein the environmental variables include atleast one of temperature, pressure, and humidity. In some examples, theflue extension is configured to screen out one or more target gases fromreaching the reference sensing device. In some examples, the primarysensing device is adapted to be exposed to a potential leak source andthe reference sensing device is adapted to be exposed to an environmentother than the potential leak source under identical environmentalvariables.

In some examples, a diameter of the flue is about 10 times a mean freepath of one or more target gases. In some examples, the method includesreceiving one or more environmental variables and correcting the firstgas concentration level reading and the second gas concentration levelreading based on the environmental variables. In some examples, themethod is carried out via at least one processor.

The foregoing illustrative summary, as well as other exemplaryobjectives and/or advantages of the disclosure, and the manner in whichthe same are accomplished, are further explained in the followingdetailed description and its accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the illustrative embodiments can be read inconjunction with the accompanying figures. It will be appreciated thatfor simplicity and clarity of illustration, elements illustrated in thefigures have not necessarily been drawn to scale. For example, thedimensions of some of the elements are exaggerated relative to otherelements. Embodiments incorporating teachings of the present disclosureare shown and described with respect to the figures presented herein, inwhich:

FIG. 1 illustrates an example schematic diagram of a standard heating,ventilation, and air conditioning unit (HVAC) system.

FIG. 2 illustrates an example schematic diagram of a conduit unit, inaccordance with one or more embodiments of the present disclosure.

FIG. 3 illustrates an example schematic diagram of a sensor assembly inaccordance with an example embodiment of the present disclosure.

FIG. 4 illustrates an example partial schematic of the sensor assemblyfor use in accordance with an example embodiment of the presentdisclosure.

FIG. 5 illustrates an example sectional view of the sensor assembly inaccordance with an example embodiment of the present disclosure.

FIG. 6 illustrates an example block diagram of a control unit inaccordance to embodiments of the present disclosure.

FIG. 7 illustrates an example flowchart of a method for operating theHVAC, for use in accordance with an example embodiment of the presentdisclosure.

FIG. 8 illustrates an example schematic diagram of a conduit unit, inaccordance with another embodiment of the present disclosure.

FIG. 9 illustrates an example schematic diagram of the sensor assemblyin accordance to embodiments of the present disclosure.

FIG. 10 illustrates an example cross-sectional view of the sensorassembly for use in accordance with an example embodiment of the presentdisclosure.

FIG. 11 illustrates an example fluid flow diagram within the sensorassembly, in accordance to embodiments of the present disclosure.

FIG. 12 illustrates an example fluid flow diagram within the sensorassembly for use in accordance with an example embodiment of the presentdisclosure.

FIG. 13 illustrates an example schematic diagram of a conduit for use inaccordance with another example embodiment of the present disclosure.

FIG. 14 illustrates an example block diagram of an HVAC configured inaccordance with an example embodiment of the present disclosure.

FIG. 15 illustrates a schematic diagram of the sensor assembly for usein accordance with an example embodiment of the present disclosure.

FIG. 16 illustrates a schematic diagram of the sensor assembly for usein accordance with an example embodiment of the present disclosure.

FIG. 17 illustrates an example flowchart of a method for operating thesensor assembly of FIG. 14 , for use in accordance with an exampleembodiment of the present disclosure.

FIG. 18 is a graph showing the voltage outputs of two oxygen sensorsduring changes in the oxygen concentration level.

FIG. 19 is a graph showing results of testing using an exampleembodiment of the present disclosure with Butane being the target gas.

FIG. 20 is a block diagram of the sensor assembly, with a flue,configured in accordance with an example embodiment of the presentdisclosure.

FIG. 21 a illustrates an example block diagram of a flue enclosed sensorassembly configured in accordance with an example embodiment of thepresent disclosure.

FIG. 21 b illustrates an example block diagram of a sensor assembly,with flue extending outside the closed system, configured in accordancewith an example embodiment of the present disclosure. and

FIG. 22 illustrates an example block diagram of a sensor assemblyconfigured in accordance with an example embodiment of the presentdisclosure.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION

Some embodiments of the present disclosure will now be described morefully hereinafter with reference to the accompanying drawings, in whichsome, but not all embodiments of the disclosure are shown. Indeed, thesedisclosures may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein. Instead, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements. Like numbers refer to like elements throughout. Theterminology used in this patent is not meant to be limiting insofar asdevices described herein or portions thereof may be attached or utilizedin other orientations.

The phrases “in one embodiment,” “according to one embodiment,” “in someembodiments,” and the like generally mean that the particular feature,structure, or characteristic following the phrase may be included in atleast one embodiment of the present disclosure, and may be included inmore than one embodiment of the present disclosure (importantly, suchphrases do not necessarily refer to the same embodiment).

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any implementation described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations.

If the specification states a component or feature “may,” “can,”“could,” “should,” “would,” “preferably,” “possibly,” “typically,”“optionally,” “for example,” “often,” or “might” (or other suchlanguage) be included or have a characteristic, that particularcomponent or feature is not required to be included or to have thecharacteristic. Such component or feature may be optionally included insome embodiments, or it may be excluded.

Various embodiments discussed herein allow for monitoring and detectionof gas leaks, such as in Heating, Ventilation, and air conditioning(HVAC) units during operation. In some examples, such refrigerantsinclude safety class A2L refrigerants such as but are not limited toR-410A, R-1234yf, R-1234ze, R-32, R-454A, R-404A, R-454C, R-455A, R-447A, R-452B, R-454B, and/or the like. A2L refrigerants/one or morerefrigerant gases are being used more often in such refrigeration unitsdue to a lower global warming potential (GWP), and therefore regulationshave been put into place in various countries to monitor leakage toavoid dangerous conditions during use. While A2L refrigerants havegenerally low toxicity and only mild flammability, large leaks can stillcause dangerous situations. Therefore, monitoring and detection of suchleaks are, in some examples, necessary for refrigerant units.

Generally, the A2L refrigerants have a vapor density greater thanambient air. Therefore, the refrigerants settle under gravity at thelowest points of the refrigeration units. Hence, the monitoring anddetection of the gases need to be performed at the lowest points (in agravitational force direction) of the refrigeration unit.

Various example embodiments of the present disclosure allow for a simpleyet effective leakage monitoring system. Additionally, as the monitoringsystems may continuously receive outputs from sensors to allow themonitoring systems to provide a self-check feature to verify that themonitoring system is operational.

While various embodiments discuss refrigeration units, variousembodiments discussed herein may also be used for other types of gasleaks, such as in heating, ventilation, and air conditioning (HVAC)applications, fire suppression systems, and/or the like usingclosed-loop cycles. For example, other such examples include, but arenot limited to inert gas leaks, natural gas leaks, propane gas leaks,butane gas leaks, carbon monoxide gas leaks, hydrocarbon gas leaks,and/or the like. Various embodiments discussed herein allow for thedetection of large-scale leaks. For example, gas leaks at or aboveapproximately 1% volume per volume.

FIG. 1 is a schematic diagram of a standard heating, ventilation, andair conditioning unit (HVAC) system 10. The HVAC system 10 is an exampleembodiment that may be included or associated with any of a variety ofcomputing devices or sensing devices. The HVAC system 10 includes acondenser unit 12 and an air handler or conduit unit 14.

One of the condenser unit 12 and conduit unit 14 may include suitablelogic and/or circuitry that may enable the condenser unit 12 tofacilitate cooling and/or heating of the ambient air (flowing throughthe HVAC system 10). For example, as shown in FIG. 2 , the condenserunit 12 may include a plurality of cooling/refrigerating pipes 16fluidly coupled to a compressor (not shown). The compressor may causeone or more refrigerant gases to flow through the plurality of coolingpipes. In some examples, a portion of the plurality of cooling pipes 16may be positioned within the conduit unit 14. Conduit unit 14 may beconfigured to facilitate the flow of the ambient air over the portion ofthe plurality of cooling pipes positioned within the conduit unit 14.The portion of the cooling pipes may facilitate the cooling/heating ofthe ambient air. The structure of the conduit unit 14 is furtherdescribed in FIG. 2 .

FIG. 2 illustrates a schematic diagram of the conduit unit 14, inaccordance with one or more embodiments of the present invention. Theconduit unit 14 includes a conduit 20, a blower or fan 30, a controlunit 40, and a sensor assembly 50. In some embodiments, the control unit40 may be communicatively coupled to the blower 30 and the sensorassembly 50.

Conduit 20 has a conduit inlet 22 and a conduit outlet 24. The conduitinlet 22 is configured to receive ambient air from the environment. Insome embodiments, the conduit inlet 22 may be fluidly coupled toadditional conduits (not shown), wherein each additional conduit isconfigured to supply ambient air into the conduit 20. Additionally, oralternatively, the conduit inlet 22 may be fluidly coupled to othercomponents of the HVAC system 10 that are configured to supply ambientair to the conduit 20. In an example embodiment, the conduit outlet 24may be configured to provide conditioned air to other components of theHVAC system 10. In some embodiments, conduit 20 may be defined by one ormore walls defining a periphery of the conduit 20.

The conduit 20 of FIG. 2 includes at least a first wall 26 and a floor28. The first wall 26 extends parallel to a vertical axis 21 of theconduit unit 14. The vertical axis 21 is defined as being parallel tothe gravitational force 18. In some embodiments, floor 28 is coupled tothe first wall 26 and extends perpendicularly to the vertical axis 21.

The blower 30 may be positioned within the conduit 20 to facilitate theflow of the ambient air through the conduit 20 and force ambient airover the plurality of cooling/refrigerating pipes 16. The blower 30 hasa blower opening 32 through which ambient air is pushed, causing anairflow 34 through the conduit 20. In some embodiments, the blower 30may include suitable logic and/or circuitry (not shown) to control thespeed and volume of airflow 34. The blower 30 may have the bloweropening 32 that faces the first end 228 of the flushing tube 170. Theblower 30 may be configured to be periodically activated in order toblow the ambient gases into the flushing tube 170.

In this embodiment, the blower 30 flushes the sensor assembly 50 everytime the blower 30 is run. Constantly flushing the sensor assembly 50clears the system of gases and maintains the sensor assembly 50baselined to the same level of refrigerant gas after each time theblower 30 is run. This is to ensure that that the sensor assembly 50 issampling the same refrigerant gas concentration as that located withinthe conduit 20.

In another embodiment, the blower 30 may be connected with the sensorassembly 50. In this embodiment, the blower 30 is configured to producean airflow through the sensor assembly 50 to flush the sensor assembly50. The blower 30 of this embodiment may be located within the conduit20 and be mechanically coupled to the sensor assembly 50 and beinstalled as a part of the sensor assembly 50. In this embodiment,activation of the blower 30 is initiated by a signal from the controlsystem 40.

In still another embodiment, the blower 30 may be connected with thesensor assembly 50 and located outside of the conduit 20. In thisembodiment, the blower 30 may be mechanically coupled to the sensorassembly 50 and be installed as a part of the sensor assembly 50. Theblower 30 of this embodiment is configured to produce an airflow throughthe sensor assembly 50.

The control unit 40 may include suitable logic and/or circuitrycommunicatively coupled to, the blower 30, and the sensor assembly 50.In some embodiments, the control unit 40 may be coupled to the condenserunit 12. The control unit 40 may be coupled to and configured to controlthe operations of the HVAC system 10. For example, the control unit 40may be configured to activate/deactivate the blower 30 and otherwisecontrol blower 30 to adjust the speed and volume of airflow 34 withinthe conduit 20. The control unit 40 may be implemented as an ApplicationSpecific Integrated Circuit (ASIC) or Field Programmable Gate Array(FPGA). In some embodiments, the control unit 40 may include electronic,electromechanical, and mechanical technologies. The structure and theoperation of the control unit 40 will be described later in conjunctionwith FIG. 6 .

In another embodiment, the control unit 40 is not configured to controlthe operations of the HVAC system. In this embodiment, the control unit40 may be configured to control an airflow through sensor assembly 50.

The sensor assembly 50 is coupled to the conduit 20 through a flooropening 29 in floor 28. The sensor assembly 50 is located below theportion of the plurality of cooling pipes 16 positioned within theconduit 20. In some embodiments, the sensor assembly 50 may be locateddirectly below the portion of the plurality of cooling pipes 16positioned within the conduit 20. In other embodiments, floor 28 mayinclude a trough (not shown) or other structure to direct the flow ofgases into the sensor assembly 50. In still other embodiments, thesensor assembly 50 may include a structure such as a trough or a funnelto be placed inside the conduit to direct the flow of gases into thesensor assembly 50.

The sensor assembly 50 may be coupled to the control unit 40 and beconfigured to provide a signal to the control unit 40 when specificpredefined gases are detected by the sensor assembly 50. In analternative embodiment, the sensor assembly 50 may be coupled to thecontrol unit 40 and be configured to provide a signal to the controlunit 40 when a specific predefined gas is not detected by the sensorassembly 50.

As such, the control unit 40 may be configured to monitor the signalreceived from the sensor assembly 50. Based on the monitoring of thesignal from the sensor assembly 50, the control unit 40 may beconfigured to activate/deactivate the blower 30 or adjust the speed andvolume of airflow 34 through the conduit 20 based on the signal from thesensor assembly 50. In another embodiment, the control unit 40 may beconfigured to automatically activate/deactivate the blower 30 withoutany intervention or association with the signal from the sensor assembly50.

FIG. 3 illustrates a schematic of the sensor assembly 50, according toembodiments illustrated herein.

FIG. 4 illustrates a sectional view of the sensor assembly 50 when aplane 80 cuts the sensor assembly 50, according to one or moreembodiments illustrated herein. The sensor assembly 50 includes a firstopening 52 and a second opening 54. The first opening 52 is coupled to asampling tube 58. In an example embodiment, the sampling tube 58 isreceived within the floor opening 29 (shown in FIG. 2 ) in floor 28. Thesensor assembly 50 includes a first filter unit 60 located over thefirst opening 52 and a second filter unit 62 located over the secondopening 54. In some examples, the first filter unit 60 may be configuredto restrict dust particles and moisture from entering within the sensorassembly 50.

The sensor assembly 50 defines a chamber 64 between the first opening 52and the second opening 54. Chamber 64 is adjacent to a gas sensor 66.The gas sensor 66 is disposed adjacent to and is connected with theelectrical circuitry 68. In some examples, the gas sensor 66 may bedisposed within chamber 64. In some examples, the gas sensor 66 isplaced along a side wall 56 of the first opening 52 or chamber 64. Thegas sensor 66 may be embodied as a plurality of gas concentrationsensors configured for detecting the concentration of one or moregaseous fluids. In various embodiments, as discussed below, the gasconcentration sensors may be electrochemical sensors configured tomonitor the concentration of one or more refrigerant gases.

The sensor assembly 50 may include a connection port 70. The connectionport 70 may be a USB or other standard electrical connector. Theconnection port 70 may be used to connect to one of the control unit 40or other device for data collection device.

FIG. 5 illustrates a fluid flow diagram within the sensor assembly 50.During operation, one or more refrigerant gases 70 pass through thesampling tube 62 into chamber 64 to reach the gas sensor 66. The gassensor 66 detects the presence of the one or more refrigerant gases 70.Owing to a higher vapor density, the one or more refrigerant gases 70may tend to slowly move within the sensor assembly 50 before egress fromthe second opening 54.

In some embodiments, the second filter 62 may be a check valve torestrict the ingress of air, from the surroundings of the sensorassembly 50, into the gas sensor assembly. The second filter 62 mayinclude a structure to restrict the egress of one or more refrigerantgases to allow a concentration of one or more refrigerant gases to buildup over time. In these embodiments, the second filter 62 may allow oneor more refrigerant gases to be dispelled from the sensor assembly 50 bya flow of ambient air, forming a positive pressure created by theactivation of the blower 30.

In some examples, the scope of the disclosure is not limited to having asingle sensor assembly or a sensor assembly having a single gas sensorcoupled to the conduit. In an example embodiment, multiple sensorassemblies 50 may be coupled to the conduit 20 without departing fromthe scope of the disclosure. In another example embodiment, the sensorassembly 50 may include multiple gas sensors 62. Further, the scope ofthe disclosure is not limited to sensing one or more refrigerant gasesto determine a leak in the plurality of refrigeration coils. In anexample embodiment, the sensor assembly 50 may be configured todetermine a concentration of oxygen to determine the leakage of one ormore refrigerant gases, as is further described in FIG. 14-22 .

In various embodiments, as discussed below, the gas sensor 66 may be anelectrochemical sensor configured to monitor the concentration of one ormore refrigerant gases, oxygen, or other gas that will be depleted asthe one or more gaseous fluids builds up in the sensor. For example, oneor more of the gas concentration sensors may be a fuel-cell liquidelectrolyte electrochemical sensor. In various embodiments, the gasconcentration sensors may employ having a plurality of electrodes, suchas a sensing electrode, a reference electrode, and a counter electrode.The sensor also includes an electrolyte that is disposed over at least aportion of each electrode in order to form an ionic pathway. One or moreleads can be coupled by electrical conductors such as wires to theelectrodes on the sensing element. The leads may extend through and beembedded within the housing. The sensor also includes a capillary/paththat can be disposed of through a substrate to allow a gas todiffuse/pass to the sensing electrode and/or the electrolyte. Theelectrodes allow for various reactions to take place to allow a currentor potential to develop in response to the presence of a target gas. Theresulting signal may then allow for the concentration of the target gasto be determined. Various sensors may be used in embodiments of thepresent disclosure, such as a liquid electrolyte electrochemical (e.g.,Consumable anode (battery) or fuel cell pump), High-Temperature Solidelectrolyte electrochemical (e.g., Zirconia or other oxygen ionconductor), and/or Fluorescence Quenching (e.g., ruthenium-based dye),optical sensors, Non-Dispersive Infrared (NDIR) sensors, opticalsensors, thermal sensors, semiconductor sensors, or the like. While thesensors discussed herein are referred to as gas concentration sensors,the sensing devices discussed herein may take the form of partialpressure sensors.

The electrical circuitry 60 of an example embodiment may also optionallyinclude a communication interface that may be any means such as a deviceor circuitry embodied in either hardware or a combination of hardwareand software that is configured to receive and/or transmit data from/toother electronic devices in communication with the sensor assembly, suchas by near field communication (NFC) or other proximity-basedtechniques. Additionally, or alternatively, the communication interfacemay be configured to communicate via cellular or other wirelessprotocols, including Global System for Mobile Communications (GSM), suchas but not limited to Long Term Evolution (LTE). In this regard, thecommunication interface may include, for example, an antenna (ormultiple antennas) and supporting hardware and/or software for enablingcommunications with a wireless communication network. Additionally oralternatively, the communication interface may include the circuitry forinteracting with the antenna(s) to cause transmission of signals via theantenna(s) or to handle receipt of signals received via the antenna(s).

In various embodiments, at least a portion of the sensor assembly 50 maybe disposed in proximity to the portion of the plurality of coolingpipes 16 within the HVAC system 10. For example, at least the sensorassembly 50 (shown in FIG. 1 ) may be proximate to the portion of theplurality of cooling pipes 16, and the electrical circuitry 68 may bedisposed elsewhere.

In various embodiments, the sensor assembly 50 may be placed insufficient proximity, such that a leakage of gas (e.g., refrigerant) mayresult in a change of the oxygen concentration. In some embodiments, thesensor assembly 50 may be disposed at a location proximate to an area ofthe portion of the plurality of cooling pipes 16 in which leakages occurmore than other locations. For example, gas leaks may occur more oftenat connection between different tubing. In various embodiments, thesensor assembly 50 may be disposed within the HVAC system 10 or thelike, such that any gas leak may reach the sensor assembly 50.

Under passive conditions (no airflow through the sensor assembly 50),gases that are heavier than air flows through the opening in the floor29 and into the sampling tube 58 of the sensor assembly 50. The heavierthan air gases collect in the chamber 64, in the vicinity of the gassensor 66. This will happen irrespective of whether the concentration inthe sampled area had subsequently changed due to either the leakstopping or remedial dilution, which will provide inaccurate sensorreadings. As such, it is important to be able to flush the sensorassembly 50 without compromising the gas sensor's ability to receive andrespond to leaking gas.

FIG. 6 illustrates a block diagram 100 of a control unit 40, accordingto one or more embodiments described herein. Control unit 40 includes aprocessor 102, a memory device 104, an Input/Output (I/O) deviceinterface unit 106, a flush control unit 108.

The processor 102 may be embodied as one or more microprocessors withaccompanying digital signal processor(s), one or more processor(s)without an accompanying digital signal processor, one or morecoprocessors, one or more multi-core processors, one or morecontrollers, processing circuitry, one or more computers, various otherprocessing elements including integrated circuits such as, for example,an application-specific integrated circuit (ASIC) or field-programmablegate array (FPGA), or some combination thereof. Although illustrated inFIG. 6 as a single processor, in an embodiment, processor 102 mayinclude a plurality of processors and signal processing modules. Theplurality of processors may be embodied on a single electronic device ormay be distributed across a plurality of electronic devices collectivelyconfigured to function as the circuitry of the HVAC system 10. Theplurality of processors may be in operative communication with eachother and may be collectively configured to perform one or morefunctionalities of the circuitry of the HVAC system 10, as describedherein. In an example embodiment, the processor 102 may be configured toexecute instructions stored in the memory device 104 or otherwiseaccessible to the processor 102. These instructions, when executed byprocessor 102, may cause the circuitry of the HVAC system 10 to performone or more of the functionalities as described herein.

Whether configured by hardware, firmware/software methods, or by acombination thereof, the processor 102 may include an entity capable ofperforming operations according to embodiments of the present disclosurewhile configured accordingly. Thus, for example, when processor 102 isembodied as an ASIC, FPGA, or the like, the processor 102 may includespecifically configured hardware for conducting one or more operationsdescribed herein. Alternatively, as another example, when the processor102 is embodied as an executor of instructions, such as may be stored inthe memory device 104, the instructions may specifically configure theprocessor 102 to perform one or more algorithms, and operationsdescribed herein.

Thus, the processor 102 used herein may refer to a programmablemicroprocessor, microcomputer, or multiple processor chip or chips thatcan be configured by software instructions (applications) to perform avariety of functions, including the functions of the various embodimentsdescribed above. In some devices, multiple processors may be provideddedicated to wireless communication functions and one processordedicated to running other applications. Software applications may bestored in the internal memory before they are accessed and loaded intothe processors. The processors may include internal memory sufficient tostore the application software instructions. In many devices, theinternal memory may be a volatile or nonvolatile memory, such as flashmemory or a mixture of both. The memory can also be located internal toanother computing resource (e.g., enabling computer-readableinstructions to be downloaded over the Internet or another wired orwireless connection).

The memory device 104 may include suitable logic, circuitry, and/orinterfaces that are adapted to store a set of instructions that isexecutable by processor 102 to perform predetermined operations. Some ofthe commonly known memory implementations include, but are not limitedto, a hard disk, random access memory, cache memory, read-only memory(ROM), erasable programmable read-only memory (EPROM) & electricallyerasable programmable read-only memory (EEPROM), flash memory, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, a compact disc read-only memory (CD-ROM), digitalversatile disc read-only memory (DVD-ROM), an optical disc, circuitryconfigured to store information, or some combination thereof. In anexample embodiment, the memory device 104 may be integrated with theprocessor 102 on a single chip without departing from the scope of thedisclosure.

The I/O device interface unit 106 may include suitable logic and/orcircuitry that may be configured to communicate with the one or morecomponents of the HVAC system 10, in accordance with one or more devicecommunication protocols such as, without limitation, I2C communicationprotocol, Serial Peripheral Interface (SPI) communication protocol,Serial communication protocol, Control Area Network (CAN) communicationprotocol, and 1-Wire® communication protocol. In an example embodiment,the I/O device interface unit 106 may communicate with the sensorassembly 50 and the blower 30. Some examples of the I/O device interfaceunit 106 may include, but are not limited to, a Data Acquisition (DAQ)card, an electrical drives driver circuit, and/or the like.

The flush control unit 108 may include suitable logic and/or circuitrythat may be configured to monitor the signal received from the sensorassembly 50, as is further described in FIG. 7 .

In an example embodiment, the signal may be indicative of aconcentration of gas accumulated within the sensor assembly 50. Forexample, the signal may be indicative of the concentration of one ormore refrigerant gases accumulated within the sensor assembly 50. Basedon the concentration of the gas within the sensor assembly 50, the flushcontrol unit 108 may be configured to activate/deactivate the blower 30,as is further described in FIG. 7 . The flush control unit 108 may beimplemented as ASIC or FPGA without departing from the scope of thedisclosure.

With additional reference to FIG. 7 , which illustrates flowchart 120 ofa method for operating the HVAC system 10, according to embodimentsillustrated herein, at step 122, the HVAC system 10 includes means suchas a control unit 40, a processor 102, and the flush control unit 108for activating the blower 30 to produce the airflow 34 of the ambientair through the conduit 20.

The plurality of cooling pipes 16 located within the conduit 20 andcoupled to the condenser unit 12 are configured to modify thetemperature of the ambient air. In some examples, due to leakage in theplurality of cooling pipes 16, one or more refrigerant gases may leakinto the conduit unit 14. Since one or more refrigerant gases areheavier than the ambient air, one or more refrigerant gases may fallfrom the plurality of cooling pipes 16 and accumulated along the floor28 or bottom of the conduit 20.

At step 124, the HVAC system 10 includes means such as a control unit40, a processor 102, and the flush control unit 108 for receiving thesignal from the sensor assembly 50. The signal is indicative of theconcentration of one or more refrigerant gases in the sensor assembly50. In an example embodiment, processor 102 is configured to determinethe concentration of one or more refrigerant gases based on the receivedsignal. In another example embodiment, the sensor assembly 50 may beconfigured to generate the signal corresponding to the concentration ofone or more refrigerant gases in the sensor assembly 50.

At step 126, the HVAC system 10 includes means such as a control unit40, a processor 102, and the flush control unit 108 for comparing thedetermined concentration of the gas with a predetermined gas thresholdvalue. In an example embodiment, the predetermined gas threshold valuemay correspond to the threshold above which the concentration of one ormore refrigerant gases is determined to be dangerous/harmful. In anexample embodiment, the predetermined gas threshold value may bepredefined during the manufacturing of the HVAC. If the flush controlunit 108 determines that the concentration of one or more refrigerantgases is less than the predetermined gas threshold value, the flushcontrol unit 108 may be configured to repeat step 124. However, if theflush control unit 108 determines that the concentration of one or morerefrigerant gases is greater than the predetermined gas threshold value,the flush control unit 108 may be configured to generate a notificationsignal, as shown in step 128. The predetermined gas threshold may beeither a maximum threshold or a minimum threshold. The predetermined gasthreshold may indicate a presence of one or more refrigerant gases orthe lack of one or more non-refrigerant gases, such as oxygen.

At step 128, the HVAC system 10 includes means such as a control unit40, a processor 102, and the flush control unit 108 for generating anotification signal that the gas threshold exceeds a threshold value. Inan example embodiment, the notification may be transmitted to auser/operator of the HVAC to indicate the one or more refrigerant gasesare leaking.

At step 130, the HVAC system 10 includes means such as a control unit40, a processor 102, and the flush control unit 108 for activating theblower 30. The blower 30 is set to run for a predetermined amount oftime. Once the blower has been activated, the sensor assembly 50 willreceive the ambient air from the conduit 20 to flush or remove leakedone or more refrigerant gases from the sensor assembly 50. The ambientair may include a mixture of the leaked one or more refrigerant gasesand the air or only the ambient air present inside the conduit 20.

After the blower 30 is activated for the predetermined amount of time,step 124 will be repeated. The controller 40 may be programmed tocompare one or more signals from the sensor assembly 50 over apredetermined timeframe and provide a warning notification signal thatthe HVAC system 10 requires maintenance. The controller 40 provideswarning of the presence of refrigerant gases and triggers the one ormore signals to initiate preventative measures to reduce the possibilityof the build-up of a dangerous gas mixture within the conduit 20.

In some embodiments, the warning notification signal includes one oflocation information, gas concentration information, and sensor assemblyfault information. In some embodiments, the warning notification signalmay include one of auditory and visual signals. In some embodiments, thewarning notification signal may regulate the blower 30 to prevent thebuildup of one or more refrigerant gases within the HVAC system 10.

Activation/operation of the blower 30 during the normal operation of theHVAC system 10 provides a regular cleaning of the sensor assembly 50 byforcing ambient air through the sensor assembly 50. This regularcleaning of the sensor assembly 50 prevents the sensor assembly frombecoming poisoned by continually flushing ambient air through the sensorassembly and removing one or more refrigerant gases that may have leakedwithin the HVAC system 10. Further, such an operation also reduces thepossibility of false positives due to the constant presence of one ormore refrigerant gases.

FIG. 8 illustrates a schematic diagram of the conduit unit 14, inaccordance with one or more embodiments of the present invention. Theconduit unit 14 of FIG. 8 includes conduit 20, the blower 30, and thecontrol unit 40 shown in FIG. 2 , and a sensor assembly 150.

The sensor assembly 150 includes a sampling tube 158 and a flushing tube170. The sensor assembly 150 is fluidly coupled to the conduit 20through both the sampling tube 158 and flushing tube 170. The samplingtube 158 is fluidly coupled to the conduit 20 through a floor opening 29in floor 28. The flushing tube 170 is fluidly coupled to the conduit 20through a wall opening 27 in the first wall 26. In an exampleembodiment, at least a portion of the flushing tube 170 may bepositioned external to the conduit 20.

In an example embodiment, the flushing tube 170 may include a first end172, a second end 174, and a middle portion 176. The first end, 172 ofthe flushing tube 170, is fluidly coupled to the second opening of thesensor assembly 150. The second end 174 of the flushing tube 170 mayinclude an internal portion 180 is positioned internal to the conduit 20and is configured to collect the airflow 34 of ambient air. In someexamples, the second end 174 of the flushing tube 170 may define a bend178 that causes the second end 174 of the flushing tube 170 to facealong a direction of the airflow 34.

In some embodiment, the second end 174 of the flushing tube 170 may bepositioned to face the blower opening 32 of blower 30. The blower 30 maybe configured to be periodically activated to blow the ambient gasesinto the flushing tube 170.

FIG. 9 illustrates a schematic of the sensor assembly 150, according toembodiments illustrated herein. The sensor assembly 150 includes a firstopening 152, and a second opening 154. The first opening 152 is coupledto a sampling tube 58, and the second opening 154 is coupled to thesecond end 174 of the flushing tube 170.

In an example embodiment, the sampling tube comprising a plurality ofcapillaries to allow diffusion of the one or more gases therethrough.

FIG. 10 illustrates a sectional view of the sensor assembly 150 when aplane 180 cuts the sensor assembly 150, according to one or moreembodiments illustrated herein. The sensor assembly 150 includes a firstfilter unit 160, a gas sensor 166, an electrical circuitry 168, and maya second filter unit (not shown). The gas sensor 166 is disposed on topof the electrical circuitry 168. The gas sensor 166 is exposed to theflushing tube 170 and the sampling tube 158. The gas sensor 166 may bedisposed in a direction perpendicular to one or more refrigerant gasesentering within the gas sensor 166. In an example embodiment, the gassensor 166 may be disposed in a direction parallel to the direction ofingress of one or more refrigerant gases. In an example embodiment, thefirst opening 152 comprises the first filter unit 160 and the secondopening 54 may include the second filter unit (not shown), the firstfilter unit and the second filter unit are configured to screen out dustand moisture from the one or more gases reaching the sensor assembly. Insome examples, the sensor assembly 150 may define chamber 164, where theflushing tube 170 and the sampling tube 158 are fluidly coupled tochamber 164. In some examples, the gas sensor 166 is located withinchamber 164.

FIG. 11 illustrates a fluid flow diagram within the sensor assembly 150,according to embodiments illustrated herein. During operation, when theblower 30 is not activated, the one or more refrigerant gases passthrough the sampling tube 158 into chamber 164 and reaches the gassensor 166 and the gas sensor 166 detects the presence of the one ormore refrigerant gases. Owing to a higher vapor density, the one or morerefrigerant gases may tend to accumulate within the sensor assembly 150.

FIG. 12 illustrates a fluid flow diagram within the sensor assembly 150,according to embodiments illustrated herein. During operation, when theblower 30 is actuated, the flushing tube 170 would receive ambient airfrom the conduit 20, which would move under the influence of the blowertoward chamber 164. Owing to the pressure of the ambient air in theflushing tube 170, the flushing tube 170 facilitates the flow of theambient air to the chamber to evacuate one or more refrigerant gasestherefrom. Also, the pressure of the ambient air in the flushing tube170 evacuates one or more refrigerant gases from chamber 164 and the gassensor 504. Such a movement of the mixture of ambient air and theresidual one or more refrigerant gases would be well below a threshold,and the sensor assembly may not be affected by the residual one or morerefrigerant gases. Thus, reducing the possibility of poisoning of thegas sensor 166 and/or reducing the changes of inaccuracies of the sensorreadings.

In some examples, the scope of the disclosure is not limited to thepositioning of the flushing tube 170 with respect to the conduit 20. Inan example embodiment, the positioning of the flushing tube 170 may varybased on the orientation of the conduit 20 without departing from thescope of the disclosure. One such example is illustrated in FIG. 13 . Inthe illustrated embodiment of FIG. 13 , both the sampling tube 158 andflushing tube 170 are fluidly coupled to a floor of the conduit 20.

In another embodiment, the flushing tube 170 may include heat exchangingvanes to cool down the ambient air entering the sensor assembly 50.

In an example embodiment, the sampling tube comprising a plurality ofcapillaries to allow diffusion of the one or more gases therethrough.

Refrigerant gases have been shown to leak through the walls andunderneath air handler units as well. Another advantage is that theflushing action removes refrigerant from the flue and the sensor, whichalso distributes fresh air around the outlet of the sensor. Thus, theflushing action dilutes the concentration of the leaked refrigerantcollecting in that area, serving as a safety mitigation factor. This isshown in FIG. 13 as an outlet at the right side of the sensor housing.In some embodiments, the flushing tube 170 may extend substantiallyparallel to a horizontal axis 190 of the conduit 20. This advantageapplies to any HVAC systems with a confined space underneath leak pointswhere the gas can collect, concentrate over time, and present anexplosion or fire concern.

In some examples, the scope of the disclosure is not limited to havingone sensor assembly coupled to the conduit. In an example embodiment,the multiple sensor assemblies may be coupled to the conduit 20, withoutdeparting from the scope of the disclosure. Further, the scope of thedisclosure is not limited to sensing the one or more refrigerant gasesto determine a leakage in the plurality of refrigeration coils. In anexample embodiment, the sensor assembly 150 may be configured todetermine a concentration of oxygen to determine the leakage of the oneor more refrigerant gases, as is further described in FIG. 14-22 .

FIG. 14 illustrates the HVAC 300 in accordance with various embodimentsof the present disclosure. As shown, the HVAC 300 may include one ormore closed-loop gas (e.g., refrigerant) coils 310 and sensor assembly150. In various embodiments, at least a portion of the sensor assembly150 may be disposed in proximity to the given closed-loop gas coil 310within the HVAC 300. For example, at least the sensor assembly 150(shown in FIG. 1 ) may be proximate to the closed-loop gas coils 310 andthe electrical circuitry may be disposed elsewhere.

In various embodiments, the sensor assembly 150 may be placed insufficient proximity, such that a leakage of gas (e.g., refrigerant) mayresult in a change of the oxygen concentration. In some embodiments, thesensor assembly 150 may be disposed at a location proximate to an areaof the closed-loop gas coils 310 in which leakages occur more than otherlocations. For example, gas leaks may occur more often at connectionbetween different tubing. In various embodiments, the sensor assembly150 may be disposed with the HVAC 300 or the like, such that any gasleak may reach the sensor assembly 150.

FIG. 15 is an example configuration of a sensor assembly 500 inaccordance with another example embodiment. As shown, a primary sensingdevice 520 and a reference sensing device 522 may be disposed within thesensor assembly 500. In various embodiments, the sensor assembly 500 maybe oriented such that the coil surface 510 is proximate to theclosed-loop gas coil 310 and a gas (e.g., refrigerant) leakage 515 in aninstance such a leakage occurs. As such, the primary sensing device 520and the reference sensing device 522 may be disposed at common position,provided the reference sensing device is exposed to ambient air with thehelp of a flue extension. In some embodiments, there may be a trade-offin performance between the leak location, gas movement, sensor location,sensitivity, and response time of the sensing device. The response timebeing defined as the time for a sensor to respond from no load to a stepchange in load.

In some embodiments, the sensor assembly 500 may include a single sensorto allow positioning of the sensor away from the gas leakage 515. Inthis embodiment, the sensor assembly 500 may include a single NDIRsensor.

In various embodiments any gas leakage 515 may reach the primary sensingdevice 520 before the reference sensing device 522. The primary sensingdevice 520 and reference sensing device 522 are configured to determinethe presence of one or more target gases, for example, oxygen, carbondioxide, the refrigerant, or another gas. As such, the first oxygenconcentration level reading captured by the primary sensing device 520may be altered due to the gas leak (e.g., the oxygen concentration maydecrease) before the second oxygen concentration level reading capturedby the reference sensing device 522 is altered. As such, in an instancein which a leakage is occurring, the first oxygen concentration levelreading may decrease more quickly than the second oxygen concentrationlevel reading.

In some embodiments, the reference sensing device 522 may also beoriented differently from the primary sensing device 520, such that thegas flowing from the potential leak is inhibited from entering thereference sensing device 522 and not inhibited from entering the primarysensing device 520 (e.g., as the arrows in FIG. 15 shown, the target gasmay flow directly into the primary sensing device 520, but may have totravel around the electrical circuitry 530 and the flue extension toaccess the reference sensing device 522). As such, the temporal effectof the gas flow may be more definitively shown by the outputs of eachsensing device. In some embodiments, a potential leak may be defined asan area susceptible to leakage. For instance, in a refrigeration unit,the potential leakage locations may include braised joints, connectionsbetween tubing, areas under mechanical and/or thermal stress, and/or thelike. In various embodiments, the potential leakage location may bedetermined via testing of specific applications.

In some embodiments, the reference sensing device 522 may be exposed toan ambient environment, such as ambient air that is outside of thesensor assembly 500 via the flue extension coupled with the referencesensing device 522. In this regard, the reference sensing device 522 maynot receive any of the target gas during a leakage instance. In such aninstance, the reference sensing device 522 may be located in an areawith similar environmental conditions to the position of the primarysensing device 520. While FIG. 15 shows only a single primary sensingdevice 520 and a single reference sensing device 522, variousembodiments may use more than two sensing devices disposed on a singlePCB and at the same location (i.e. not spaced apart).

In various embodiments, at least a portion of the electrical circuitry530 may be disposed within the sensor assembly 500. As shown, theprimary sensing device 520 and/or the reference sensing device 522 maybe connected to the electrical circuitry 530 via pins on the sensingdevices configured to engage with sockets on the electrical circuitry530. Various embodiments may employ different connection methods, suchas pads configured on the sensing devices and pogo pins on theelectrical circuitry 530. Various embodiments discussed herein may haveany number of different standard electrical interconnects between thesensing devices and the electrical circuitry 530. In some embodiments,the primary sensing device 520 and/or the reference sensing device 522may be equipped with short range communication capabilities to allow thesensing devices to communicate with the electrical circuitry 530remotely. In various embodiments, the electrical circuitry 530 may beconfigured to receive oxygen concentration level readings from theprimary sensing device 520 and the reference sensing device 522. In someembodiments, the electrical circuitry 530 may store one or more of theoxygen concentration level readings, such that the oxygen concentrationlevel readings may be monitored over time (e.g., the first oxygenconcentration level readings and the second oxygen concentration levelreadings may diverge over time due to a leak). In some embodiments, timesequence data may be used to determine leak instances. In variousembodiments, the monitoring may be continuous. Alternatively, themonitoring may occur at intervals based on the gas leakage application(e.g., some gas leaks may not be as dangerous and intermittentmonitoring may be cost saving).

FIG. 16 is another example configuration of the sensor assembly 500 inaccordance with an example embodiment. As shown, the primary sensingdevice 520 and the reference sensing device 522 may be disposed withinthe same sensor assembly 500. As shown, the primary sensing device 520and the reference sensing device 522 may be disposed at the sameposition in the gas leak environment.

In some embodiments, the reference sensing device 522 may be equippedwith a filter 524 configured to remove one or more target gases (e.g.,refrigerants) from the gas entering the reference sensing device 522. Insome embodiments, the filter 524 may be configured to absorb one or moretarget gases (e.g., one or more refrigerant gases) that pass therein.For example, the filter 524 may be an absorber. In some embodiments, thefilter 524 may be positioned between the closed-loop gas coil 310 andthe reference sensing device 522, such that any gas combination thatreaches the reference sensing device has passed through the filter 524(e.g., removing some or all of the one or more refrigerant gases).

In various embodiments, the filter 524 may be activated carbons ofvarious types. In some such embodiments, the activated carbons may beimpregnated with other chemicals depending on the species to beabsorbed. In some embodiments, molecular sieves, zeolites, and/or otherwell know filter families may be used. In some embodiments, the targetgas may dictate the design of the filter 524 (e.g., Sofnocarb powder maybe used in an instance in which Butane is the target gas). In someembodiments, the filter 524 may be designed to absorb the target gaspermanently or to slow down its passage to the reference sensing device,such that a temporal difference arises in the response compared to theprimary sensing device.

In some embodiments, the primary sensing device 520 and the referencesensing device 522 may be a single sensor with a plurality of gas feeds.For example, the single sensor may have a primary sensing device gasfeed without a filter 524 and a reference sensing device gas feed thatmay have a filter 524. In such an embodiment, the sensing device mayhave a mechanical switch configured to alternate access to a sensingelectrode from the primary sensing device gas feed to the referencesensing device gas feed during operation. In such an embodiment, variouspumping devices may be used to move the gas from the gas feeds to thesensing electrode. During operation, the mechanical switch may alternatebetween the primary sensing device gas feed and the reference sensingdevice gas feed and the differences between the first oxygen levelreading from the primary sensing device gas feed and the second oxygenlevel reading may be compared as discussed herein with a two sensingdevice system.

In some embodiments, as gas (e.g., refrigerant) leaks, the first oxygenconcentration level reading of the primary sensing device 520 may beginto decrease, while the second oxygen concentration level reading of thereference sensing device 522 remains approximately constant (or at leastdecreases more slowly). In some instances in which a gas leak issufficiently large, the filter 524 may be become overwhelmed (e.g.,fully saturated) at a specific point, such that the second oxygenconcentration level reading of the reference sensing device 522 maybegin to decrease in line with a sensing device without a filter. Insuch an embodiment, the time lag between the decrease of the firstoxygen concentration level and the second oxygen concentration level mayindicate that a gas leakage is occurring. Additionally, various otherinformation may be determined via the individual outputs of the sensingdevices.

In various embodiments, at least a portion of the electrical circuitry530 may be disposed within the sensor assembly 500 as the primarysensing device 520 and the reference sensing device 522). As shown, theprimary sensing device 520 and/or the reference sensing device 522 maybe connected to the electrical circuitry 530 via pins on the sensingdevices configured to engage with sockets on the electrical circuitry530. Various embodiments may employ different connection methods, suchas pads configured on the sensing devices and pogo pins on theelectrical circuitry 530. Various embodiments discussed herein may haveany number of different standard electrical interconnects between thesensing devices and the electrical circuitry 530. In some embodiments,the primary sensing device 520 and/or the reference sensing device 522may be equipped with short range communication capabilities to allow thesensing devices to communicate with the electrical circuitry 530remotely. In various embodiments, the electrical circuitry 530 may beconfigured to receive oxygen concentration level readings from theprimary sensing device 520 and the reference sensing device 522. In someembodiments, the electrical circuitry 530 may store one or more of theoxygen concentration level readings, such that the oxygen concentrationlevel readings may be monitored over time (e.g., the first oxygenconcentration level readings and the second oxygen concentration levelreadings may diverge over time due to a leak). In various embodiments,the monitoring may be continuous. Alternatively, the monitoring mayoccur at intervals based on the gas leakage application (e.g., some gasleaks may not be as dangerous and intermittent monitoring may be costsaving).

Referring now to FIG. 17 , an example embodiment of the presentdisclosure includes a flow diagram 600 for the electrical circuitry 530,the processor 532, the sensor assembly 24, or the like, to monitor anddetect a gas (e.g., refrigerant) leak. While various embodiments of thesensor assembly may include at least one processor 532, variousembodiments of the sensor assembly may be analog systems, such that theprimary sensing device 20 and the reference sensing device 22 may be incommunication with a differential amplifier and/or ratio amplifier anduse a comparator to determine an instance in which a leakage isoccurring. As such, the operations of FIG. 17 may be carried out by ananalog system.

Referring now to Block 610 of FIG. 17 , the sensor assembly 500, such asthe electrical circuitry 530, the processor 532, or the like, mayinclude means for receiving a first oxygen concentration level readingof a given area. In various embodiments, as discussed above, the firstoxygen concentration level reading may be captured by the primarysensing device 520. In various embodiments, the first oxygenconcentration level reading may be affected by the environmentalconditions, such as temperature or the like. Additionally, in someembodiments, the first oxygen concentration level reading may beaffected by the introduction of new gases (e.g., such as a gas leakcausing the oxygen concentration to decrease).

Referring now to Block 620 of FIG. 17 , the sensor assembly 500, such asthe electrical circuitry 530, the processor 532, or the like, mayinclude means for receiving a second oxygen concentration level readingof the given area. In various embodiments, as discussed above, the firstoxygen concentration level reading may be captured by the referencesensing device 522. In various embodiments, the reference sensing device522 may be positioned in similar environmental conditions, such that theeffects of the environmental conditions on the second oxygenconcentration level reading may be similar or the same to the effects ofthe environmental conditions on the first oxygen concentration levelreading.

In various embodiments, however, the reference sensing device 522 may beconfigured such that a gas leakage 515 may have a different effect onthe second oxygen concentration level reading from the reference sensingdevice 522 than on the first oxygen concentration level reading from theprimary sensing device 520. For example, in an instance in which thereference sensing device 522 is coupled with the flue which does notallow the leaking gas to pass through and reach the reference sensingdevice. The second oxygen concentration level reading may begin todecrease a time after the first oxygen concentration level readingbegins to decrease, as the gas (e.g., refrigerant) may take longer toreach the reference sensing device 522. Alternatively, in an instance inwhich the reference sensing device 522 is equipped with a filter 524(e.g., FIG. 16 ) or the flue, the second oxygen concentration level maynot decrease, due to a gas leak, while the first oxygen concentrationlevel may decrease due to said gas leak.

Referring now to Block 630 of FIG. 5 , the sensor assembly 500, such asthe electrical circuitry 530, the processor 532, or the like, mayinclude means for comparing the first oxygen concentration level readingand the second oxygen concentration level reading. In variousembodiments, the difference in the first oxygen concentration levelreading and the second oxygen concentration level reading may correlateto the amount of gas leakage. In some embodiments, the comparison may beat a given time (e.g., at an instance in which the primary sensingdevice 520 has a lower oxygen concentration level reading than thereference sensing device 522). In some embodiments, the first oxygenconcentration level reading and the second oxygen concentration levelreading may be monitored over time, such that changes in the firstoxygen concentration level reading and the second oxygen concentrationlevel reading may indicate that a gas leak is occurring.

In an example analog embodiment, the primary sensing device 520 and thereference sensing device 522 may measure an output current, that isconverted to a voltage, the individual output voltages may be amplifiedto eliminate any noise. As such, the voltages may be compared usingeither a differential or a ratio. In such an analog embodiment, acomparator may be used to determine a leak has occurred.

Referring now to Block 640 of FIG. 17 , the sensor assembly 500, such asthe electrical circuitry 530, the processor 532, or the like, mayinclude means for causing a transmission of a signal that a gas (e.g.,refrigerant) leak is occurring in an instance in which the first oxygenconcentration level reading and the second oxygen concentration levelreading have a reading difference greater than a threshold difference.

In various embodiments, the determination that a gas leak may beoccurring may be based on the comparison of the first oxygenconcentration level reading and the second oxygen concentration levelreading. In some embodiments, the amount of target gas (e.g.,refrigerant) allowable to leak may be based on the flammability of saidgas. As such, the threshold difference may be lower than theflammability level of the target gas. For example, in an instance theflammability level is 10%, the threshold difference may be 1%. Forexample, a 1% change in the oxygen concentration (e.g., from 20.9%oxygen concentration to 20.7% oxygen concentration) may indicate 1%leakage gas (e.g., refrigerant) concentration. In various embodiments,the difference between the first oxygen concentration level reading andthe second oxygen concentration level reading may correlate to thechange in oxygen concentration (e.g., the primary sensing device 20 andthe reference sensing device 22 may be configured such that only anintroduction of the target gas (e.g., a gas leak) may cause the firstoxygen concentration level reading and the second oxygen concentrationlevel reading to differ substantially). In various embodiments, thethreshold difference may be between approximately 5% and 10% of thevolume of oxygen concentration level.

FIG. 18 is a graph showing the similar oxygen concentration readings oftwo sensors, such as the oxygen sensor used in various embodimentsherein, during changes to the oxygen level in the air. As shown, the twosensors, which are being exposed to the same air, shown almost identicalreadings and therefore can be relied upon to shown substantial changesin the oxygen level. The S2/S1 line shown is the ratio of the Sensor 2reading and the Sensor 1 reading. As shown, the ratio is approximately 1and therefore any change to one of the sensor readings (e.g., in aninstance a gas leakage occur and the primary sensing device 520experiences a decrease in oxygen before the reference sensing device522), may be represented by a change of the ratio from approximately 1.

FIG. 19 illustrates the output of a sensor assembly, similar to thesensor assembly shown in FIG. 16 , wherein the reference sensing device522 is equipped with the flue and a filter 524. In the graph shown inFIG. 19 , the target gas is butane. As shown, the target gas isintermittently being introduced to the sensor assembly and each time thetarget gas is introduced, the primary sensing device 520 experiences aspike above the nominal voltage (e.g., spikes 700A-700D), while thevoltage of the reference sensing device 522 remains approximatelyconstant due to the flue which does not allow passage of the gastherethrough or the filter absorbing the butane. In the example shown, adifferential is used to show an instance in which a leak is occurringand are shown as spikes 710A-710D.

FIG. 20 illustrates a block diagram of the sensor assembly similar tosensor assembly shown in FIG. 16 except the introduction of a flue 800fitted on one side of the reference sensing device 522. The flue 800enables the reference sensing device to be exposed to fresh air and awayfrom a leak environment 810 or the area having the leaking gas. On theother hand, the primary sensing device 520 is exposed to A2L gas leaksbeing heavy in nature. In this regard, a differential signal can becalculated based on the exposure of leaking gas to the primary sensingdevices 520 and ambient air to the reference sensing device 522. To thisend, the flue 800 allows diffusion or passage of ambient air and keepsreference sensing device 522 away from the leaking gas. In this regard,the efficiency of the gas detection can be significantly enhanced basedon the detection of variation in the gas concentration in a workingenvironment.

In one exemplary embodiment, the primary sensing device 520 and thereference sensing device 522 are co-located to detect A2L gas leaks inAC systems. This differential sensor system has long lifetime,self-calibration capacity, and high reliability. The sensors areprogrammed to detect gas concentration after a predetermined time andcompare based on the detected concentration. In this regard, based onthe change in concentration of ambient air (or oxygen gas) the gasdetection system re-calibrates the threshold values. Further, the systemis highly reliable as both the primary sensing device 520 and thereference sensing device 522 are co-located in such a manner that theseare exposed to identical environmental variables such as temperature,pressure, humidity having different gas exposure. Thus, the detectorsystem detects minor changes in gas concentration which are depicted bythe differential signal.

In one another embodiment, two oxygen sensors are used to measure thedecrease in oxygen concentration due to a leak in A2L gas. In case of noleak, both sensors are exposed to ambient air resulting in zerodifferential signal. However, to detect A2L leak in an environment,primary sensing device 520 is exposed to the area having the leaking gasin order to detect change in oxygen concentration. At the same time, theflue 800 fitted reference sensing device 522 detects concentration ofoxygen present in ambient air. In this regard, every time the primarysensing device 520 detects change in oxygen concentration, it iscompared with the concentration of oxygen in ambient air. A controlcircuitry receives the signals from the primary sensing device 520 andreference sensing device 522 and compares the signals to determine adifferential signal. Thereby, this differential signal indicates thechange in oxygen concentration and in other words concentration of A2Lgas in that environment. For example, a 1% change in the oxygenconcentration (e.g., from 20.9% oxygen concentration to 20.7% oxygenconcentration) may indicate 1% leakage gas (e.g., refrigerant)concentration can be detected with accuracy by the gas detection system.

In one another exemplary embodiment, the flue 800 includes a filter (notshown) fitted at an entrance of the flue 800 for preventing the passageof A2L to pass through the flue. This results in increased sensitivityas the reference sensing device 522 detects concentration of ambient airafter filtering the A2L gases.

In one another exemplary embodiment, the gas detector system includesdual oxygen sensors, both configured to operate in an AC system. Thesensor 1 is the primary sensing device 520 subjected to detect depletionof oxygen gas by having an exposure to the one or more refrigerant gases(e.g. A2L). Further, sensor 2 is the reference sensing device 522 whichis fitted with the flue 800 extending to clean air (absence of one ormore refrigerant gases on the order of >10 min). Both sensors work incollaboration to generate a steady state differential signal.

In one another exemplary embodiment, the gas detector system is designedto be independent of potential false alarms due to changes intemperature, pressure and humidity. Unlike in conventional dual oxygensensor systems, the present gas detector does not trigger false alarms.Conventional oxygen sensors were operable to detect the concentration ofoxygen in the environment and trigger alarms when the detectedconcentration level exceeds a predetermined level without calculatingthe relative oxygen concentration. The relative oxygen concentration iscalculated by comparing the sensed oxygen concentration with a referencethreshold. The reference threshold is calibrated based on theconcentration of ambient oxygen at that time.

In one another exemplary embodiment, the recalibration of thepredetermined threshold referred to as continuous self-check reading ofO₂ level. In this regard, any type of O₂ dilution with heavy gases aredetected, rendering this system applicable to different gases.

In one another exemplary embodiment, the positioning of the two sensorsin proximity to each other results in a compact design, whereby thereference sensing device is co-located with all electrics, minimizingunit size and maximizing compensation performance. By having compactconfiguration, the errors or losses due to electric losses are minimizedwhich results in highly accurate and sensitive signal output.

In one another exemplary embodiment, when the leak rate is high, thedual sensors are positioned at a bottom of a cabinet and leak ishappening at the top of the flue. The flue is having a cylindrical shapehaving a cross section with an inner diameter of about 0.625 inches(0.0158 m) and a height of about 6 inches (0.152 m). The referencesensing device 522 exposed to air at top of the cabinet. Thedifferential output is the difference between the primary sensing device520 and the reference sensing device 522 with the flue 800.

In one another exemplary embodiment, the reference sensing device 522can compensate for temperature, pressure, and humidity changes. Anadvantage is that any effects upon the senor of other ambient gases,such as CO₂, can be compensated to provide more accurate readings. Thisis especially useful in the case of oxygen sensors, but it also appliesto other sensor technologies and interferents.

Further, design of the flue 800 is versatile from a system's designstandpoint. In this regard, the flue 800 of different heights anddifferent diameter can be used without interrupting a mean free path ofthe target gas.

In one another exemplary embodiment, the flue is a passive element andcan be easily integrated to the existing systems of reference sensor.Further, no pump is associated with the sensing system in order to pushthe ambient air into the reference sensing device 522.

In another exemplary embodiment, the gas collection systems has aplurality of flues leading from various locations to the sensor.Multiple flues enable multiple sensing locations within the air handlerunit, providing a safety factor for the HVAC manufacturers to ensureleaked gas is being detected independent of sensor location.

FIG. 21 a is a block diagram of a flue 900 enclosed sensor assemblyconfigured in accordance with an example embodiment of the presentdisclosure. In this regard, the sensor system is placed inside furnacenear metering device. The primary sensing device 520 is exposed toconditions inside a furnace or other enclosed area 902 and the referencesensing device is modified with the flue 900 which can be run away frompotential source of leak. In this manner, the flue 900 can be adjustedeither at maximum height inside furnace or can be run outsidecontainment of furnace as shown in FIG. 21 b.

Referring to FIG. 21 b , discloses a block diagram of the sensorassembly with the flue 904 extending outside the closed system 906. Inboth the configurations of FIG. 21 a and FIG. 21 b , the flue 904,extending away from the area having the leaking gas, is configured toprovide ambient air to the reference sensing device 522.

FIG. 22 is a block diagram of a sensor assembly configured in accordancewith an example embodiment of the present disclosure. As shown in FIG.22 , to determine the oxygen concentration, one end of a flue 910 iscoupled with the primary sensing device 520 and a second end reaching tothe gas leak environment. In this regard, the gas detector can detectthe leak in gas by exposing the primary sensing device 520 to the leakenvironment via the flue 910 and the reference sensing device is adaptedto be exposed to the ambient air. In one exemplary embodiment, the fluecan have any shape or size depending on the requirements and dimensionsof the flue 910 are such that, it allows the gas to diffuse or passthrough freely without encroaching the mean free path of the gas. Inthis regard, the gas detector can be placed outside the cabinet,furnace, or container without compromising with the sensing quality ofthe gas detector. This arrangement helps in extended life span of thesensors and increased sensitivity due to the arrangement of the primaryand reference sensing device on a printed circuit board (PCB).

In one another exemplary embodiment, the signal sensor is modified withthe flue and exposed to conditions inside furnace by running the flueinto the container or furnace where the one or more refrigerant gases isleaking. To this end, the reference sensor is open to conditions outsidefurnace containment and are not be subject to influence from therefrigerant leak

In another exemplary embodiment of the present invention, by placing theprimary and reference sensing device close enough to each other, signaldelay can be eliminated to a greater extent due to signal loss inelectronic circuits or transmissions. Thereby, with this structuralarrangement, the signal to noise ratio can be increased as compared toconventional differential sensors and which results in improved responsetime. In this manner, by minimizing the delay time either due tostructural constraints such as relative placement of the primary andreference sensing device or due to the transmission or electroniccircuits, the sensitivity of the gas detector can be increased multipletimes.

Further, in accordance with some example embodiments, the sensorassembly for determining a composition of one or more gases comprising asensor assembly includes a primary sensing device and a referencesensing device located in proximity to the primary sensing device, aflue coupled with the reference sensing device at one end of thereference sensing device, wherein the reference sensing device isconfigured to determine, via the flue, a first oxygen concentrationlevel of a given area, wherein the primary sensing device is configuredto determine a second oxygen concentration level of the given area.

According to some example embodiments described herein, a controlcircuitry, electrically coupled with the primary sensing device and thereference sensing device, configured to receive the determined first andsecond oxygen concentration level from the primary sensing device andthe reference sensing device, compare the first oxygen concentrationlevel and the second oxygen concentration level, and based on thecomparison, in an instance in which the second oxygen concentrationlevel and the first oxygen concentration level have a difference greaterthan a threshold difference, cause a transmission that a gas leak isoccurring.

Further, in accordance with some example embodiments, the primarysensing device and the reference sensing device are located within asensor assembly and exposed to identical exposure of environmentalvariables.

Further, in accordance with some example embodiments, the gas detectorfurther comprises a filter positioned on one side of the flue, whereinthe filter is configured to screen out one or more gases from reachingthe reference sensing device.

Further, in accordance with some example embodiments, the primarysensing device is adapted to be exposed to a potential leak source andthe reference sensing device is adapted to be exposed to an environmentother than the potential leak source under identical environmentalvariables.

Further, in accordance with some example embodiments, the thresholddifference is based on between 5% and 10% of a volume of oxygenconcentration level. To this end, the threshold difference is based on aflammability level of a gas. Further, the target gas is a refrigerantgas.

Further, in accordance with some example embodiments, the sensorassembly is further configured to receive one or more environmentalvariables and correcting the first oxygen concentration level readingand the second oxygen concentration level reading based on theenvironmental variables. The control circuitry comprising at least oneprocessor, the at least one processor having computer coded instructionstherein, with the computer instructions configured to, when executed,cause the operations of the sensor assembly by providing an alertsignal. In this regard, the sensor assembly is a fully analog system ora digital system.

Further, in accordance with some example embodiments, a size of the flueis designed such that a mean free path of the gases being sensed is notencroached. In this regard, a diameter of the flue is about 100 timesthe mean free path of one of the measured gas and ambient air. Further,a response time of the sensing is adapted to remain within acceptablelimits based on a length of the flue, wherein the length of the flue isabout 0.1 meter to 3 meters. In some embodiments, the diameter of theflue is greater than 10 mm.

Further, in accordance with some example embodiments, a method ofdetermining a gas leak with a sensor assembly, the sensor assemblycomprising a primary sensing device and a reference sensing device, themethod comprising determining, via a flue extension coupled with areference sensing device, a first oxygen concentration level of a givenarea and determining, via a primary sensing device, a second oxygenconcentration level of the given area. A control circuitry forcomparing, the determined first oxygen concentration level and thesecond oxygen concentration level and triggering an alarm ornotification based on the comparison, in an instance in which the firstoxygen concentration level reading and the second oxygen concentrationlevel reading have a difference greater than a threshold difference.

Further, in accordance with some example embodiments, exposing each ofthe primary sensing device and the reference sensing device to identicalenvironmental variables, wherein the environmental variables include atleast one of temperature, pressure, and humidity.

Further, in accordance with some example embodiments, the flue extensionis configured to screen out one or more target gases from reaching thereference sensing device.

Further, in accordance with some example embodiments, the primarysensing device is adapted to be exposed to a potential leak source andthe reference sensing device is adapted to be exposed to an environmentother than the potential leak source under identical environmentalvariables. A diameter of the flue is about 100 times a mean free path ofone or more target gases.

Further, in accordance with some example embodiments, receiving one ormore environmental variables and correcting the first oxygenconcentration level reading and the second oxygen concentration levelreading based on the environmental variables. The method is carried outvia at least one processor.

An advantage of using a flue on either the sensing and/or the referencesensor(s) is that the sensors are allowed to passively access gas from adifferent part of the HVAC system. This also means that the sensors canbe located in less challenging environmental conditions. For example,the region where a gas leak might accumulate could be subject to a harshenvironment, such as wide temperature and/or RH swings and the sensorscan be connected through the flue with these areas. Using flues asdescribed allows the sensors to be mounted in a more benign region thathas a consistent temperature. The sensor may also be spaced from wherethe gas leak might accumulate to provide an environment that has a loweroperating temperature. Spacing the sensors from the harsh environmentallow the sensors to provide a more accurate performance, minimizecompensation and referencing difficulties to reduce false alarms andincrease sensor life.

Various embodiments discussed herein allow for monitoring and detectionof gas leaks, such as in refrigeration units during operation. Whilevarious embodiments discuss refrigeration units, various embodimentsdiscussed herein may also be used for other types of gas leaks, such asin HVAC applications and/or the like using closed-loop cycles.Refrigeration units include closed-loop cooling/refrigerant coils thatcontain flammable refrigerants. A2L refrigerants are being used moreoften in such refrigeration units due to a lower global warmingpotential (GWP) and therefore regulations have been put into place invarious countries to monitor leakage to avoid dangerous conditionsduring use. While A2L refrigerants have generally low toxicity and onlymild flammability, large leaks can still cause dangerous situations.Therefore, monitoring and detection of such leaks are necessary forrefrigerant units. Various embodiments of the present disclosure allowfor a simple, yet effective leakage monitoring system.

In some embodiments, certain ones of the operations above may bemodified or further amplified. Furthermore, in some embodiments,additional optional operations may be included. Modifications,additions, or amplifications to the operations above may be performed inany order and in any combination.

Many modifications and other embodiments set forth herein will come tomind to one skilled in the art to which these disclosures pertain havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. Therefore, it is to be understood that thedisclosure is not to be limited to the specific embodiments disclosedand that modifications and other embodiments are intended to be includedwithin the scope of the appended claims. Moreover, although theforegoing descriptions and the associated drawings describe exampleembodiments in the context of certain example combinations of elementsand/or functions, it should be appreciated that different combinationsof elements and/or functions may be provided by alternative embodimentswithout departing from the scope of the appended claims. In this regard,for example, different combinations of elements and/or functions thanthose explicitly described above are also contemplated as may be setforth in some of the appended claims. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

The invention claimed is:
 1. A sensor assembly comprising: a firstsensing device, a second sensing device located in proximity to thefirst sensing device, wherein the second sensing device is orienteddifferently from the first sensing device such that one of the firstsensing device and the second sensing device determines a firstconcentration level of a first gas in a first area simultaneously withthe other of the first sensing device and the second sensing devicedetermining a second concentration level of the first gas in a secondarea; and a flue coupled with one of the first sensing device and thesecond sensing device to provide a pathway for the first gas in thefirst area to access the one of the first sensing device and the secondsensing device, wherein the one of the first sensing device and thesecond sensing device coupled to the flue is configured to determine thefirst concentration level of the first gas in the first area and theother of the first sensing device and the second sensing device isconfigured to determine the second concentration level of the first gasin the second area.
 2. The sensor assembly of claim 1, further comprisesan electrical circuit electrically coupled with the first sensing deviceand the second sensing device, configured to: receive the firstconcentration level and the second concentration level, compare thefirst concentration level and the second concentration level todetermine a reading difference between the first concentration level andthe second concentration level, and based on the comparison, in aninstance in which the reading difference is greater than a predeterminedthreshold difference, cause a transmission of a signal identifying thata leak of the first gas is occurring.
 3. The sensor assembly of claim 1,wherein the first sensing device and the second sensing device areconfigured to be exposed to substantially identical environmentalvariables.
 4. The sensor assembly of claim 1, further comprises a filterpositioned and configured to screen out one or more gases from reachingthe second sensing device.
 5. The sensor assembly of claim 1, whereinthe first sensing device is adapted to be exposed to a potential leaksource in the first area.
 6. The sensor assembly of claim 2, wherein thepredetermined threshold difference is based on between 5% and 10% of avolume of the first gas.
 7. The sensor assembly of claim 2, wherein thepredetermined threshold difference is based on a flammability level ofthe first gas.
 8. The sensor assembly of claim 1, wherein the first gasis a refrigerant.
 9. The sensor assembly of claim 1, wherein the sensorassembly is further configured to receive one or more environmentalvariables and correcting the first concentration level reading and thesecond concentration level reading based on the one or moreenvironmental variables.
 10. The sensor assembly of claim 1, furthercomprising a control circuitry comprising at least one processor, the atleast one processor having computer coded instructions configured to,when executed, provide an alert signal.
 11. The sensor assembly of claim1, wherein the sensor assembly is one of a fully analog system and adigital system.
 12. The sensor assembly of claim 1, wherein the flue hasan opening therethrough, the opening having cross-sectional area,wherein a square root of the cross-sectional area yields a length thatis larger than a mean free path of the first gas.
 13. The sensorassembly of claim 12, wherein the square root of the cross-sectionalarea yields the length that is larger than about 100 times the mean freepath of the first gas.
 14. The sensor assembly of claim 1, wherein aresponse time of the sensing is adapted to remain within acceptablelimits based on a length of the flue, wherein the length of the flue isabout 0.1 meter to 3 meters.
 15. A method of determining a gas leak witha sensor assembly, the sensor assembly comprising a first sensing deviceand a second sensing device that is oriented differently from the firstsensing device, the method comprising: determining, via a flue extensioncoupled with the second sensing device, a first gas concentration levelof a first gas in a given area; determining, via the first sensingdevice, a second gas concentration level of a second gas in the givenarea, wherein the first sensing device is oriented differently from thesecond sensing device such that the first sensing device determines thesecond gas concentration level of the second gas in the given areasimultaneously with the second sensing device determining the first gasconcentration level of the first gas in the given area; comparing, usinga control circuitry, the determined first gas concentration level andthe second gas concentration level; and based on the comparison, in aninstance in which the first gas concentration level reading and thesecond gas concentration level reading have a difference greater than athreshold difference, causing a transmission of a differential outputthat the gas leak is occurring.
 16. The method of claim 15, furthercomprising exposing each of the first sensing device and the secondsensing device to identical environmental variables, wherein theenvironmental variables include at least one of temperature, pressure,and humidity.
 17. The method of claim 15, wherein the flue extension isconfigured to screen out one or more target gases from reaching thesecond sensing device.
 18. The method of claim 15, wherein the firstsensing device is adapted to be exposed to a potential leak source andthe second sensing device is adapted to be exposed to an environmentother than the potential leak source under identical environmentalvariables.
 19. The method of claim 15, wherein a diameter of a flue isabout 10 times a mean free path of one or more target gases.
 20. Themethod of claim 15, further comprising receiving one or moreenvironmental variables and correcting the first gas concentration levelreading and the second gas concentration level reading based on the oneor more environmental variables.